LEAD MOBILIZATION FROM A CLAYEY SOIL IN RELATION TO CARBONATE CONTENT

The efficiency of removing lead from two contaminated clayey soils of different carbonate content was studied in the laboratory. Water and a queous solutions of sodium chloride, acetic, hydrochloric and nitric a cids and ethylenediaminetetraacetic acid disodium salt (EDTA-Na-2) wer e examined for their potential extractive capabilities in batch and co lumn tests. Pb concentrations in the soil ranged from 13,000 to 49,000 mg/kg mainly distributed in the carbonate and the exchangeable fracti ons of the soil. The effects of varying the soil/solution ratio and th e concentrations of the extraction agents have been studied. Results s how that removal of Pb from the exchangeable fraction is readily achie ved when little or no carbonates are present. Mobilization of the Pb i n the carbonate fraction of the soil is only feasible with acid soluti ons or concentrated EDTA-Na-2 solutions.